Patterned magnetic recording head having a gap pattern with substantially elliptical or substantially diamond-shaped termination pattern

ABSTRACT

A thin-film magnetic recording head utilizing a timing based servo pattern is fabricated by sputtering a magnetically permeable thin film onto a substrate. A gap pattern, preferably a timing based pattern, is defined by the thin film. The gap pattern includes termination patterns or endpoints that are elliptical or diamond-shaped.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 10/683,809, entitled “Patterned Magnetic RecordingHead with Termination Pattern Having a Curved Portion,” filed on Oct.10, 2003, now issued U.S. Pat. No. 7,196,870, which is acontinuation-in-part of U.S. patent application Ser. No. 09/922,546,filed Aug. 3, 2001, now issued U.S. Pat. No. 6,678,116, which is acontinuation of U.S. patent application Ser. No. 09/255,762, filed Feb.23, 1999, now issued U.S. Pat. No. 6,269,533, each of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to magnetic recording heads and moreparticularly to a method of making thin-film magnetic heads forimprinting servo patterns on a magnetic media.

BACKGROUND OF THE INVENTION

While a variety of data storage mediums are available, magnetic taperemains a preferred forum for economically storing large amounts ofdata. In order to facilitate the efficient use of this media, magnetictape will have a plurality of data tracks extending in a transducingdirection of the tape. Once data is recorded onto the tape, one or moredata read heads will read the data from those tracks as the tapeadvances, in the transducing direction, over the read head. It isgenerally not feasible to provide a separate read head for each datatrack, therefore, the read head(s) must move across the width of thetape (in a translating direction), and center themselves over individualdata tracks. This translational movement must occur rapidly andaccurately.

In order to facilitate the controlled movement of a read head across thewidth of the media, a servo control system is generally implemented. Theservo control system consists of a dedicated servo track embedded in themagnetic media and a corresponding servo read head which correlates themovement of the data read heads.

The servo track contains data, which when read by the servo read head isindicative of the relative position of the servo read head with respectto the magnetic media in a translating direction. In one type oftraditional arrangement, the servo track was divided in half. Data wasrecorded in each half track, at different frequencies. The servo readhead was approximately as wide as the width of a single half track.Therefore, the servo read head could determine its relative position bymoving in a translating direction across the two half tracks. Therelative strength of a particular frequency of data would indicate howmuch of the servo read head was located within that particular halftrack.

While the half track servo system is operable, it is better suited tomagnetic media where there is no contact between the storage medium andthe read head. In the case of magnetic tape, the tape actually contactsthe head as it moves in a transducing direction. Both the tape and thehead will deteriorate as a result of this frictional engagement; thusproducing a relatively dirty environment. As such, debris will tend toaccumulate on the read head which in turn causes the head to wear evenmore rapidly. Both the presence of debris and the wearing of the headhave a tendency to reduce the efficiency and accuracy of the half trackservo system.

Recently, a new type of servo control system was created which allowsfor a more reliable positional determination by reducing the signalerror traditionally generated by debris accumulation and head wear. U.S.Pat. No. 5,689,384, issued to Albrect et al. on Nov. 19, 1997,introduces the concept of a timing-based servo pattern, and is hereinincorporated by reference in its entirety.

In a timing-based servo pattern, magnetic marks (transitions) arerecorded in pairs within the servo track. Each mark of the pair will beangularly offset from the other. Virtually any pattern, other thanparallel marks, could be used. For example, a diamond pattern has beensuggested and employed with great success. The diamond will extendacross the servo track in the translating direction. As the tapeadvances, the servo read head will detect a signal or pulse generated bythe first edge of the first mark. Then, as the head passes over thesecond edge of the first mark, a signal of opposite polarity will begenerated. Now, as the tape progresses no signal is generated until thefirst edge of the second mark is reached. Once again, as the head passesthe second edge of the second mark, a pulse of opposite polarity will begenerated. This pattern is repeated indefinitely along the length of theservo track. Therefore, after the head has passed the second edge of thesecond mark, it will eventually arrive at another pair of marks. At thispoint, the time it took to move from the first mark to the second markis recorded. Additionally, the time it took to move from the first mark(of the first pair) to the first mark of the second pair is similarlyrecorded.

By comparing these two time components, a ratio is determined. Thisratio will be indicative of the position of the read head within theservo track, in the translating direction. As the read head moves in thetranslating direction, this ratio will vary continuously because of theangular offset of the marks. It should be noted that the servo read headis relatively small compared to the width of the servo track. Becauseposition is determined by analyzing a ratio of two time/distancemeasurements, taken relatively close together, the system is able toprovide accurate positional data, independent of the speed (or variancein speed) of the media.

By providing more than one pair of marks in each grouping, the systemcan further reduce the chance of error. As the servo read head scans thegrouping, a known number of marks should be encountered. If that numberis not detected, the system knows an error has occurred and variouscorrective measures may be employed. Once the position of the servo readhead is accurately determined, the position of the various data readheads can be controlled and adjusted with a similar degree of accuracy.

When producing magnetic tape (or any other magnetic media) the servotrack is generally written by the manufacturer. This results in a moreconsistent and continuous servo track, over time. To write thetiming-based servo track described above, a magnetic recording headbearing the particular angular pattern as its gap structure, must beutilized. As it is advantageous to minimize the amount of tape that isdedicated to servo tracks, to allow for increased data storage, and itis necessary to write a very accurate pattern, a very small and veryprecise servo recording head must be fabricated.

Historically, servo recording heads having a timing-based pattern havebeen created utilizing known plating and photolithographic techniques. Ahead substrate is created to form the base of the recording head. Then,a pattern of photoresist is deposited onto that substrate. Thephotoresist pattern essentially forms the gap in the head. Therefore,the pattern will replicate the eventual timing-based pattern. After thepattern has been applied a magnetically permeable material such as NiFeis plated around the photoresist pattern. Once so formed, thephotoresist is washed away leaving a head having a thin film magneticsubstrate with a predefined recording gap.

Alternatively, broad beam ion milling is used to form a first layerhaving a relatively large gap. A pattern of photoresist is applied in aninverse of the above described pattern. That is, photoresist is appliedeverywhere except where the timing based pattern (gap) is to be formed.Ion milling is used to cut the gap through the first layer. Then anadditional layer of the magnetically permeable material is deposited byplating over the first layer and a narrow gap is formed into this layerby the above described photolithographic process. This approach producesa more complicated head with a horizontally-processed or pancake-stylethin film coil. The broad beam ion milling of the write pole does notproduce an optimal gap structure.

While the above techniques are useful in producing timing-basedrecording heads, they also limit the design characteristics of the finalproduct. In the first method, only materials which may be plated can beutilized, such as NiFe (Permalloy). Generally, these materials do notproduce heads that have a high wear tolerance. As such, these heads willtend to wear out in a relatively short time. In addition, this class ofmaterials have a low magnetic moment density (10 kGauss for NiFe), orsaturation flux density, which limits their ability to record on veryhigh coercivity media.

The second method also relies on plating for the top magnetic layer andis therefore limited to the same class of materials. In addition, theuse of broad beam ion milling makes the fabrication of such a headoverly complex. The photoresist pattern can be applied relativelyprecisely, thereby forming a channel over the gap. However, thetraditional ion milling technique is rather imprecise and as the ionspass through that channel they are continuously being deflected.Conceptually, in any recording gap, so cut, the relative aspect ratiosinvolved prevent a precise gap from being defined. In other words, thisis a shadowing effect created by the photoresist and causes the gap inthe magnetically permeable material to be angled. Generally, thesidewalls of the gap will range between 45°-60° from horizontal. Thisintroduces a variance into the magnetic flux as it exits the gap,resulting in a less precise timing based pattern being recorded onto theservo track.

Therefore, there exists a need to provide a magnetic recording headcapable of producing a precise timing-based pattern. Furthermore, itwould be advantageous to produce such a head having a tape bearingsurface which is magnetically efficient as well as wear resistant andhence a choice of sputtered rather than plated materials are required.Thus, it is proposed to use a fully dry process to fabricate atime-based head using predominantly iron nitride based alloys.

BRIEF SUMMARY OF THE INVENTION

The present invention, in one embodiment, is a magnetic recording headfor generating servo tracks on a magnetic medium. The magnetic recordinghead includes a substrate having a generally planar first surface and amagnetically-permeable thin film deposited onto the first surface. A gappattern is defined by the thin film, and the gap has correspondingtermination patterns having at least one curved portion.

The present invention, according to another embodiment, is a gap patternfor a magnetic recording head. The gap pattern includes a pair ofnon-parallel, longitudinally extending gaps having a width andterminating in at least one termination pattern, wherein the terminationpattern has at least one curved portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side planar view of a substrate bearing a magnetic thinfilm.

FIG. 2 is a top planar view of the substrate shown in FIG. 1.

FIG. 3 is top planar view of a portion of thin film, bearing indicia ofa gap to be milled.

FIG. 4 is a schematic diagram of a FIB milling a gap into a thin film.

FIG. 5 is a top planar view of a thin film having gaps milled by a FIB.

FIG. 6 is a side sectional view taken about line VI-VI.

FIG. 7 is a top planar view of a thin film having gaps milled by a FIB.

FIG. 8 is side sectional view taken about line VII-VII.

FIG. 9A is a top planar view of a portion of thin film having a gap andendpoints milled by a FIB.

FIGS. 9B-9E show various configurations for the termination patterns orendpoints shown in FIG. 9A.

FIG. 9F shows an effect of a termination pattern configured to include arounded pattern.

FIG. 9G shows an effect of a termination pattern configured with onlysharp corners.

FIGS. 9H-9K show further various configurations for the terminationpatterns or endpoints shown in FIG. 9A.

FIG. 10 is a top planar view of a substrate bearing gaps and air bleedslots.

FIG. 11 is an end planar view of a substrate bearing air bleed slots.

FIG. 12 is a side planar view of a magnetic recording head.

FIG. 13 is an end planar view of a magnetic recording head.

FIG. 14 is a partial perspective view of thin film layer bearing a setof time based or angled recording gap pairs.

FIG. 15 shows an exemplary configuration of a terminating pattern withcircular endpoints of an amplitude-based servo head.

DETAILED DESCRIPTION

The present invention is a method of making a thin film magneticrecording head using a focused ion beam (“FIB”) to mill out gaps in thetape bearing surface. Referring to FIG. 1, a substrate 10 is created byglass bonding two C-shaped ferrite blocks 12 to a medially disposedceramic member 14. The sizes and relative proportions of the ferriteblocks 12 and ceramic member 14 may vary as dictated by the desiredparameters of the completed recording head. Furthermore, the choice ofmaterials may also vary so long as blocks 12 remain magnetic whilemember 14 remains magnetically impermeable.

A layer of magnetically permeable material is deposited as a thin film16 across an upper surface of each of the ferrite blocks 12, as well asthe upper surface of the ceramic member 14. The magnetically permeablethin film 16 will become the tape bearing and data writing surface forthe magnetic head 5 (see FIGS. 12 & 13). As such, it is desirable toform the layer of thin film 16 from a material which has a relativelyhigh magnetic moment density (greater or equal to about 15 kGauss) andis also wear resistant. An exemplary material for this purpose is FeN oralternatively Sendust™. For example, FeN has a magnetic moment densityon the order of 19 to 20 kGauss and is resistant to the frictionaldeterioration caused by continuous tape engagement. Any of the alloys inthe iron nitride family, such as iron aluminum nitride, iron tantalumnitride, etc., and including any number of elements, are also ideallysuited. FeXN denotes the members of this family, wherein X is a singleelement or a combination of elements, as is known in the art.

FeXN is created by sputtering a FeX alloy (or simply Fe) in a nitrogenrich environment. It is not available in quantities sufficient forplating. Furthermore, even if so available, the FeXN would decomposeduring the electrolytic plating process. This is in stark contrast tothe simple alloys which may be readily utilized in electrolytic platingtechniques. Therefore, while it is advantageous to use alloys, such asFeXN, magnetic recording heads cannot be formed with them, in anypreviously known plating process. In addition, the most desirable alloysto use are often composed of three of more elements. Plating isgenerally limited to the so called binary alloys, and as explained aboveis not conducive to binary gaseous alloys, such as FeN. The use ofsputtering in combination with the use of a FIB, not only allows any ofthese materials to be used but also produces a better wearing magneticthin film with a higher saturation flux density and of sufficientpermeability for use as a servo write head.

Referring again to FIG. 1, the thin film 16 is sputtered onto thesurface of the ferrite blocks 12 and the ceramic member 14. Prior to thesputtering process, the surface is polished and prepared in a mannerknown to those skilled in the art. If desired, the surface may be groundto produce a slight curvature. This curvature will facilitate smoothcontact between the tape and the completed head 5 as the tape movesacross the tape bearing surface.

The thickness of the deposited thin film 16 determines the efficiency ofthe magnetic head and also its predicted wear life. The thicker the tapebearing surface (thin film 16) is, the longer the head will last.Conversely, the thicker the magnetic film, the longer it will take toprocess or etch with a FIB and it will also process less precisely.Therefore, the thin film should be deposited in a thickness of about 1to 5 mm. Ideally, the thickness will be about 2 to 3 mm.

FIG. 2 is a top view of the substrate 10 and in particular the majorsurface of magnetic thin film 16 with the underlying ceramic member 14shown in dashed lines. The area 18 is defined by the upper surface ofthe ceramic member 14 (the magnetic sub-gap) and is where theappropriate gaps will eventually be milled.

Referring to FIG. 3, only area 18 is shown. Within area 18, some indicia20 of the eventual gap positions are laid down. It should be noted thattwo diamond shaped gaps are to be milled as shown in FIG. 3; however anyshape and any number of gaps could be created. Indicia 20 is simply anindication of where the FIB is to mill. One way of accomplishing this isto place a layer of photoresist 22 down and define the indicia 20 with amask. Using the known techniques of photolithography, a layer ofphotoresist 22 will remain in all of area 18 except in the thin diamonddefined by indicia 20. Alternatively, the photoresist area could besubstantially smaller than area 18, so long as it is sufficient todefine indicia 20. The photoresist differs in color and height from thethin film 16 and therefore produces the visually discernible pattern.This pattern is then registered with the FIB control system through agraphical interface; thus delineating where the FIB is to mill. Thephotoresist serves no other purpose, in this process, than to visuallyidentify a pattern. As such, many alternatives are available. Any highresolution printing technique capable of marking (without abrading) thesurface of the thin film 16 could be used. Alternatively, the patterncould be created completely within the FIB control system. That is,numerical coordinates controlling the path of the FIB and representingthe pattern could be entered; thus, obviating the need for any visualindicia to be placed onto the magnetic thin film 16. Finally, a visualpattern could be superimposed optically onto the FIB graphical image ofthe substrate 10, thereby producing a visually definable region to millwithout actually imprinting any indicia onto the substrate 10.

In any of the above described ways, the FIB 24 is programmed to trace apredefined pattern, such as the diamond indicia 20 shown in FIG. 3. TheFIB will be orientated in a plane orthogonal to the major surface of thethin film 16.

FIG. 4 is a sectional view of FIG. 3, taken about line IV-IV andillustrates the milling process utilizing FIB 24. The upper surface ofthe thin film 16 has been coated with a thin layer of photoresist 22.The visual indicia 20 of the diamond pattern is present, due to the areaof that indicia 20 being void of photoresist. The FIB 24 has alreadymilled a portion of the pattern forming gap 30. The FIB as shown hasjust begun to mill the right half of the pattern. The beam of ions 26 isprecisely controlled by the predefined pattern which has been enteredinto the FIB's control system. As such, the beam 26 will raster back andforth within the area indicated by indicia 20. The beam 26 willgenerally not contact a significant amount of the photoresist 22 andwill create a gap 30 having vertical or nearly vertical side walls. Thewidth of the ion beam is controllable and could be set to leave apredefined amount of space between the edge of the side wall and theedge of the indicia 20. The FIB 24 will raster back and forth until allof the indicia 20 have been milled for that particular head.

After the FIB 24 has milled all of the gap(s) 30, the photoresist 22 iswashed away. Alternatively, any other indicia used would likewise beremoved. FIG. 5 illustrates area 18 of substrate 10 after the photoresist 22 has been removed. Thin film 16 is exposed and has preciselydefined gaps 30 milled through its entire depth, down to the ceramicmember 14. FIG. 6 is a sectional view of FIG. 5 taken about line VI-VIof FIG. 5 and illustrates the milled surface of gap 30. The gap 30 isprecisely defined, having vertical or nearly vertical walls.

Referring to FIG. 14, a partial perspective view of a time basedrecording head 5 is shown. The major surface 50 of thin film 16 lies ina plane defined by width W, length L, and depth D. D is the depositedthickness of the magnetic film 16. The FIB will always mill through thinfilm 16 through a plane substantially perpendicular to the major surface50 which would also be parallel to depth D. By conventional standards,the gap 30 will have a magnetic gap depth equal to depth D, thethickness of the deposited film, and a gap width equal to width W and agap length (L′) equal to the span of gap 30 in the direction shown.

The upper surface of thin film 16, shown in FIG. 7, represents one ofmany alternative time based patterns which may be created using a FIB24. Here, gaps 30 will be milled in exactly the same fashion asdescribed above, except that indicia 20, when utilized, would haveformed the pattern shown in FIG. 7. FIG. 8 is a sectional view takenabout line VII-VII of FIG. 7 and shows how gap 30 continues to haveprecisely defined practically vertical sidewalls. Furthermore, the upperhorizontal surface 32 of ceramic member 14 is also precisely defined.

FIG. 9A illustrates yet another pattern which may be defined using FIB24. Here, gap 30 is in the shape of an augmented diamond. Rather thandefining a diamond having connected corners, gap 30 is milled to havetermination patterns or endpoints 34, 35, 36 and 37. Creating endpoints34, 35, 36 and 37 increases the definition of the finished recordedpattern near the ends of the track by helping to maintain nearly thefull magnetic field to the end of the pattern. Several different shapesare possible for the termination patterns or endpoints 34, 35, 36, and37. The rectangular shape shown in 9A, in some situations, may result inwriting of the magnetic media slightly outside of the gap pattern.Specifically, in these instances, the sharp corners may cause a highconcentration of magnetic flux that causes writing of the magneticmedia. The termination patterns or endpoints 34, 35, 36, 37 are formedusing any technique known in the art.

FIGS. 9B-9E show various configurations for the termination pattern orendpoint 34. The configuration shown in FIGS. 9B-9E may also be appliedto one or more of the other termination patterns or endpoints 35, 36,and 37. The configurations shown in FIGS. 9B-9E include rounded cornersto prevent build-up of magnetic flux, which in turn prevents writingoutside of the gap pattern. The termination patterns may be any suitableshape having at least one curved portion. The termination patterns maybe used to terminate a gap pattern formed using any technique known inthe art. As shown in FIG. 9B, the endpoint 34 is generally square-shapedand includes two inside corners 38 a and 38 b and two outside corners 38c and 38 d. In the embodiment shown, the outside corners 38 c, 38 d arerounded by replacing the square corner with an arc. As shown in FIG. 9B,the arc is a partial circle (the remainder of which is shown by thedashed line) having a center set slightly in from the point ofintersection of the two sides of the endpoint 34. In another embodiment,the insider corners 38 a, 38 b are also rounded in the same manner asthe outside corners 38 c, 38 d. In one embodiment, the endpoint 34 isgenerally rectangular-shaped. In one embodiment, the rounded corners areformed from a circle having a diameter of between about 10% and about50% of the length of the side of the endpoint 34. In another embodiment,the rounded corners are formed from a circle having a diameter of about30% of the length of the side of the endpoint 34. In one embodiment, forexample, the sides of the termination box or endpoint 34 are about 6.5microns and the diameter of the circle used to round the corners isabout 2 microns. In the embodiment wherein the outside corners 38 c, 38d are rounded, the centers of the circles may be set about 5 micronsapart.

FIG. 9C shown another configuration for the endpoint 34. As shown inFIG. 9C, all four corners 38 a, 38 b, 38 c, 38 d are rounded in theshape of three-quarters of a circle. In this embodiment, the corners arerounded to correspond to a circle centered on or about the point ofintersection of the sides of the endpoint 34. In another embodiment,only the outside corners 38 c, 38 d are rounded as shown. In oneembodiment, the endpoint 34 is generally rectangular-shaped. FIG. 9Dshows another configuration of the endpoint 34 in which the corners aresimply rounded using an arc corresponding to a quarter circle. Again,any of all of the corners 38 a, 38 b, 38 c, 38 d may be rounded. Thediameter of the circle corresponding to the rounded corners shown inFIGS. 9C and 9D may vary. In one embodiment, the circle has a diameterof between about 10% and about 50% of the length of the side of theendpoint 34. In another embodiment, the circle has a diameter of about30% of the length of the side of the endpoint 34.

FIG. 9E shows yet another configuration of the termination pattern orendpoint 34. The endpoint 34 may be defined by any curved surface 39. Asshown in FIG. 9E, the endpoint 34 is a circle. The circle may have anydiameter greater than the perpendicular distance between the walls ofthe gap 30. In one embodiment, the diameter of the circle is frombetween about 1.1 to about 4 times greater than the perpendiculardistance between opposing walls of the gap 30. In another embodiment,the diameter of the circle is about 2 times greater than theperpendicular distance between opposing walls of the gap 30. In oneembodiment, the circle has a diameter of from about 5 to about 7microns. This diameter range of 5 to 7 microns approximates the effectof the similarly sized termination pattern configured as a rectangularbox (as shown in FIG. 9A) in terms of keeping the magnetic flux fromleaking around the track edges. However, the a termination pattern usingsharp corners does not prevent leakage as well as a termination patterusing the rounded corners. This effect is shown in FIG. 9F which showsthe effect of a termination pattern with rounded corners and FIG. 9G,which has termination corners with sharp edges.

FIGS. 9H, 9I, and 9J show yet further configurations of the terminationpattern or endpoint 34. The endpoint 34 may be defined by a curvedsurface forming substantially an ellipse. That is, the terminationpattern or endpoint 34 may be elliptical-shaped. In one embodiment, asillustrated in FIG. 9H, the elliptical-shaped endpoint 60 may have alength 62 substantially perpendicular to the width 64 of the gap 30. Inan alternative embodiment, as illustrated in FIG. 9I, theelliptical-shaped endpoint 66 may have a length 68 substantiallyparallel to the width 64 of the gap 30. In yet other embodiments, asshown in FIG. 9J for example, the elliptical-shaped endpoint 70 may beconfigured at any angle 72 to the width 64 of the gap 30.

FIG. 9K shows another configuration of the termination pattern orendpoint 34. In one embodiment, the endpoint 34 may be generallydiamond-shaped. In other embodiments, the termination pattern orendpoint 34 may be generally in the shape of a rectangle, square, otherparallelogram, or polygon. In yet further embodiments, the terminationpattern or endpoint 34 may be any polygon oriented at an angle such thatthe features of the polygon do not produce a magnetic field high enoughto record transitions. In one embodiment, the edges of thediamond-shaped, or other polygon-shaped, endpoint are at, or near, aforty-five degree (45°) angle relative to the magnetic flux, generallyillustrated as 80. In other embodiments, the edges of thediamond-shaped, or other polygon-shaped, endpoint are at any othersuitable angle relative to the magnetic flux of the gap 30. In furtherembodiments, one or more of the outside corners 74 may be rounded, aspreviously discussed. In one embodiment, the rounded corners are formedfrom a circle having a diameter of between about 10% and about 50% ofthe length of a side of the endpoint 34. In another embodiment, therounded corners are formed from a circle having a diameter of about 30%of the length of a side of the endpoint 34.

The next step in the fabrication process is to create air bleed slots 40in the tape bearing surface of the substrate 10, as shown in FIG. 10.Once substrate 10 has been fabricated into a recording head, magnetictape will move across its upper surface in a transducing direction, asshown by Arrow B. Therefore, the air bleed slots 40 are cutperpendicular to the transducing direction. As the tape moves over therecording head at relatively high speed, air entrainment occurs. Thatis, air is trapped between the lower surface of the tape and the uppersurface of the recording head. This results from the magnetic tape,comprised of magnetic particles affixed to a substrate, beingsubstantially non-planar on a microscopic level. As the tape moves overthe recording head, the first air bleed slot encountered serves to skiveoff the trapped air. The second and subsequent slots continue thiseffect, thus serving to allow the tape to closely contact the recordinghead. As the tape passes over the recording gap(s) 30, it is also heldin place by the other negative pressure slot 42, 43 encountered on theopposite side of the gap(s) 30. Therefore, there is a negative pressureslot 42, 43 located on each side of the recording gap(s) 30.

FIG. 11 is a side view of the substrate 10, as shown in FIG. 10. Theupper surface of the substrate 10 has a slight curvature or contour.This acts in concert with the air bleed slots to help maintain contactwith the magnetic tape. The air bleed slots 40 are cut into thesubstrate 10 with a precise circular saw, as is known by those skilledin the art. The air bleed slots 40 are cut through thin film 16, whichis present but not visible in FIG. 11. Alternatively, the air bleedslots 40 could be cut prior to the thin film 16 having been deposited.

Substrate 10 has been longitudinally cut, thus removing a substantialportion of the coupled C-shaped ferrite blocks 12 and ceramic member 14.This is an optional step which results in an easier integration of thecoils and ferrite blocks. FIG. 13 illustrates how a backing block 46 isbonded to substrate 10. The backing block 46 is composed of ferrite oranother suitable magnetic material. Wiring is wrapped about the backingblock 46 thus forming an electrical coil 48. With this step, thefabrication process has been completed and a magnetic recording head 5has been produced.

In operation, magnetic recording head 5 is secured to an appropriatehead mount. Magnetic tape is caused to move over and in contact with thetape bearing surface of the head 5, which happens to be the thin filmlayer 16. At the appropriate periodic interval, electrical current iscaused to flow through the coil 48. As a result, magnetic flux is causedto flow (clockwise or counterclockwise in FIG. 13) through the backblock 46, through the ferrite blocks 12, and through the magnetic thinfilm 16 (as the ceramic member 14 minimizes a direct flow from oneferrite block 12 to the other causing the magnetic flux to shunt throughthe permeable magnetic film). As the magnetic flux travels through themagnetic thin film 16, it leaks out through the patterned gaps 30, thuscausing magnetic transitions to occur on the surface of the magnetictape, in the same pattern and configuration as the gap 30 itself.

Referring to FIGS. 10 and 12, it can be seen that the width of the head5 (or substrate 10) is substantially larger than a single patterned gap30. This allows the recording head to bear a plurality of patterned gaps30. For example, FIG. 10 illustrates a substrate 10 having fiverecording gaps 30 which could then write five servo trackssimultaneously. More or less can be utilized as desired and the finalsize of the head 5 can be adjusted to whatever parameters are required.

Rather than cutting the substrate 10 as shown in FIG. 11 and applying acoil as shown in FIG. 13, the substrate 10 could remain whole and thecoils could be added to the C-shaped ferrite blocks 12, as they areshown in FIG. 1.

The above head fabrication process has been described with respect to amagnetic recording head employing a timing-based servo pattern. However,the process could be applied equally well to any type of surface thinfilm recording head. For example, the head fabrication process can beapplied to an amplitude-based servo head. An exemplary configuration ofa terminating pattern with circular endpoints of an amplitude-basedservo head is shown in FIG. 15. That is, those of ordinary skill in theart will appreciate that the FIB milling of the gaps could accommodateany shape or pattern, including the traditional single gap used inhalf-track servo tracks.

Those skilled in the art will further appreciate that the presentinvention may be embodied in other specific forms without departing fromthe spirit or central attributes thereof. In that the foregoingdescription of the present invention discloses only exemplaryembodiments thereof, it is to be understood that other variations arecontemplated as being within the scope of the present invention.Accordingly, the present invention is not limited in the particularembodiments which have been described in detail therein. Rather,reference should be made to the appended claims as indicative of thescope and content of the present invention.

Although the present invention has been described with reference topreferred embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1. A magnetic recording head for generating servo tracks on a magneticmedium, the magnetic recording head comprising: a substrate having agenerally planar first surface; a magnetically-permeable thin filmdisposed on the first surface; and a gap pattern defined by the thinfilm, the gap pattern having at least one termination pattern, thetermination pattern being at least one of substantially elliptical orsubstantially diamond-shaped.
 2. The device of claim 1, wherein the gaphas nearly parallel side walls.
 3. The device of claim 1, wherein thetermination pattern is substantially elliptical and has a length that isnon-orthogonal to a width of the gap pattern.
 4. The device of claim 1,wherein the termination pattern is substantially elliptical and has alength substantially orthogonal to the width of the gap pattern.
 5. Thedevice of claim 1, wherein the gap pattern is formed by removing aportion of the thin film using a focused ion beam oriented in a planeperpendicular to the plane of the first surface.
 6. The device of claim1, wherein the gap pattern is a timing-based servo pattern.
 7. Thedevice of claim 1, wherein the gap pattern is an amplitude-based servopattern.
 8. A gap pattern for a magnetic recording head, the gap patterncomprising a pair of non-parallel, longitudinally extending gaps havinga width and terminating in at least one termination pattern, wherein theshape of the termination pattern comprises at least one of an ellipseand a diamond.
 9. The gap pattern of claim 8, wherein the shape of thetermination pattern is an ellipse having a length that is non-orthogonalto the width of the gaps.
 10. The gap pattern of claim 8, wherein theshape of the termination pattern is an ellipse having a lengthsubstantially perpendicular to the width of the gaps.
 11. The gappattern of claim 8, wherein the shape of the termination pattern is adiamond, wherein the outside corners of the diamond are rounded.
 12. Thegap pattern of claim 11, wherein the rounded corners correspond to acircle having a diameter of from about 10% to about 50% of the length ofa side of the termination pattern.
 13. The gap pattern of claim 12,wherein the rounded corners correspond to a circle having a diameter ofabout 30% of the length of a side of the termination pattern.
 14. Thegap pattern of claim 8, wherein the gap pattern is a timing-based servopattern.
 15. The gap pattern of claim 8, wherein the gap pattern is anamplitude-based servo pattern.
 16. Magnetic media imprinted with a servopattern comprising a plurality of gap patterns which comprise a pair ofnon-parallel, longitudinally extending gaps having a width, andterminating at least one gap pattern with at least one terminationpattern, wherein a width of the termination pattern is greater than thewidth of the longitudinally extending gap of the at least one gappattern terminated with the at least one termination pattern.
 17. Themagnetic media of claim 16, wherein the termination pattern is generallyelliptical.
 18. The magnetic media of claim 16, wherein the terminationpattern is generally diamond-shaped.
 19. The magnetic media of claim 16,wherein the servo pattern is a timing-based servo pattern.